Isotopic Dependence of the Nuclear Caloric Curve

TL;DR

This study investigates how isotopic composition affects the nuclear caloric curve, finding that chemical freeze-out temperatures are largely independent of A/Z ratios, with minor Coulomb effects near multifragmentation onset.

Contribution

It provides new experimental data on the isotopic dependence of the nuclear caloric curve using relativistic projectile fragmentation.

Findings

Freeze-out temperatures are nearly invariant with A/Z.

Small Coulomb effects (~0.6 MeV) observed near multifragmentation.

Consistent with predictions for expanded nuclear systems.

Abstract

The A/Z dependence of projectile fragmentation at relativistic energies has been studied with the ALADIN forward spectrometer at SIS. A stable beam of 124Sn and radioactive beams of 124La and 107Sn at 600 MeV per nucleon have been used in order to explore a wide range of isotopic compositions. Chemical freeze-out temperatures are found to be nearly invariant with respect to the A/Z of the produced spectator sources, consistent with predictions for expanded systems. Small Coulomb effects (\Delta T \approx 0.6 MeV) appear for residue production near the onset of multifragmentation.